1. Field of the Invention
This invention relates to a photographic processing composition in concentrated slurry form for use in the processing of photographic silver halide photosensitive materials.
2. Prior Art
Photographic black-and-white silver halide photo-sensitive material after exposure is generally processed through the steps of development, fixation and washing, which use processing solutions such as black-and-white developer, fixer, and wash water. On the other hand, photographic color silver halide photosensitive material after exposure is generally processed through the steps of color development, delivering, washing, and stabilization, which use processing solutions such as color developer, bleaching solution, bleach-fixer, fixer, wash water, and stabilizing solution.
These processing solutions are prepared using various chemicals most of which are normally solid.
Some processing solutions must be prepared by the user prior to use. Since unskilled users must be taken into account, such formulations are delivered to the user in concentrate form which requires only a dilution step. Processing compositions in liquid state, however, lack compactness and give rise to liquid leakage and other problems during transportation.
Processing compositions in solid state meet the requirement of compactness. One typical processing composition in solid state is a powdery composition. Powdery processing compositions, however, suffer from problems of scattering, adhesion, and leftover of powder. Tableting and granulation were proposed to eliminate these problems. Processing compositions in tablet or granule form have the problem that if tablets or granules are formed to high hardness in order to prevent them from collapsing to cause dusting, they lose the ease of dissolution. Despite the advantage of compactness, solid processing compositions are cumbersome to handle, for example, a solution preparing step being required.
Paste-form photographic processing compositions were also proposed. For example, Publication of International Patent Application No. 57-500485 discloses a photographic processing concentrate comprising a discontinuous solid phase distributed in a continuous liquid phase, the solid phase comprising fine solid particles interlaced in the form of a stable three-dimensional reticulated structure imparting shear-rate thinning, and the liquid phase being present in an amount extremely smaller than the necessary amount to form a solution of the solid phase, but sufficient to impart paste-like consistency. Because of its high viscosity at low shear rate, this concentrate, however, has to be subjected to mechanical shear or extruded in order to take the contents (paste) out of the container for admission into a processor tank, with a special tool being required. Also because of its high viscosity at low shear rate, the paste mass is unsusceptible to fine division, substantially decelerating the rate of dissolution upon dilution. Once the paste is attached to the inner wall of a dissolving tank, dilution becomes quite difficult. Incompletely dissolved paste particles are entrained in the solution and will attach to photographic film, causing trouble. In this way, high viscosity at low shear rate makes it difficult to handle in preparation steps, resulting in low productivity.
U.S. Pat. No. 2,735,774 discloses a fixer concentrate having fixer components suspended in a water-soluble colloidal gel of alginate. U.S. Pat. No. 2,784,086 discloses a developer concentrate comprising fine powdery developing and alkaline agents in a concentration of 0.5 to 10% in water and suspended as a concentrate paste in a colloidal gel of a compound selected from alginic acid, alginic acid salts, and alginic acid esters. These concentrates, however, have high viscosity and require an operation of extruding the concentrate from the container by a mechanical force when it is to be admitted from the container into a dissolving tank of a processor. The concentrate attached to the inner wall of the container is more difficult to take out. Feed of an accurate amount of the concentrate is not expectable, resulting in considerable variations of photographic quality.